TY - JOUR
T1 - Penetration depth of low-coherence enhanced backscattered light in subdiffusion regime
AU - Subramanian, Hariharan
AU - Pradhan, Prabhakar
AU - Kim, Young L.
AU - Backman, Vadim
N1 - Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2007/4/26
Y1 - 2007/4/26
N2 - The mechanisms of photon propagation in random media in the diffusive multiple scattering regime have been previously studied using diffusion approximation. However, similar understanding in the low-order (subdiffusion) scattering regime is not complete due to difficulties in tracking photons that undergo very few scatterings events. Recent developments in low-coherence enhanced backscattering (LEBS) overcome these difficulties and enable probing photons that travel very short distances and undergo only a few scattering events. In LEBS, enhanced backscattering is observed under illumination with spatial coherence length Lsc less than the scattering mean free path ls. In order to understand the mechanisms of photon propagation in LEBS in the subdiffusion regime, it is imperative to develop analytical and numerical models that describe the statistical properties of photon trajectories. Here we derive the probability distribution of penetration depth of LEBS photons and report Monte Carlo numerical simulations to support our analytical results. Our results demonstrate that, surprisingly, the transport of photons that undergo low-order scattering events has only weak dependence on the optical properties of the medium (ls and anisotropy factor g) and strong dependence on the spatial coherence length of illumination, Lsc relative to those in the diffusion regime. More importantly, these low-order scattering photons typically penetrate less than ls into the medium due to the low spatial coherence length of illumination and their penetration depth is proportional to the one-third power of the coherence volume (i.e., [ls π Ls2] 13).
AB - The mechanisms of photon propagation in random media in the diffusive multiple scattering regime have been previously studied using diffusion approximation. However, similar understanding in the low-order (subdiffusion) scattering regime is not complete due to difficulties in tracking photons that undergo very few scatterings events. Recent developments in low-coherence enhanced backscattering (LEBS) overcome these difficulties and enable probing photons that travel very short distances and undergo only a few scattering events. In LEBS, enhanced backscattering is observed under illumination with spatial coherence length Lsc less than the scattering mean free path ls. In order to understand the mechanisms of photon propagation in LEBS in the subdiffusion regime, it is imperative to develop analytical and numerical models that describe the statistical properties of photon trajectories. Here we derive the probability distribution of penetration depth of LEBS photons and report Monte Carlo numerical simulations to support our analytical results. Our results demonstrate that, surprisingly, the transport of photons that undergo low-order scattering events has only weak dependence on the optical properties of the medium (ls and anisotropy factor g) and strong dependence on the spatial coherence length of illumination, Lsc relative to those in the diffusion regime. More importantly, these low-order scattering photons typically penetrate less than ls into the medium due to the low spatial coherence length of illumination and their penetration depth is proportional to the one-third power of the coherence volume (i.e., [ls π Ls2] 13).
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U2 - 10.1103/PhysRevE.75.041914
DO - 10.1103/PhysRevE.75.041914
M3 - Article
C2 - 17500928
AN - SCOPUS:34247568477
VL - 75
JO - Physical Review E
JF - Physical Review E
SN - 2470-0045
IS - 4
M1 - 041914
ER -